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A key feature that distinguishes cancer cells from all other cells is their capability to spread throughout the body. Although how cancer cells collectively migrate by following molecular rules which influence the state of cell-cell adhesion contacts has been comprehensively formulated, the impact of physical interactions on cell spreading remains less understood. Cumulative effects of physical interactions exist as the interplay between various physical parameters such as (1) tissue surface tension, (2) viscoelasticity caused by collective cell migration, and (3) solid stress accumulated in the cell aggregate core region. This review aims to point out the role of these physical parameters in cancer cell spreading by considering and comparing the rearrangement of various mono-cultured cancer and epithelial model systems such as the fusion of two cell aggregates. While epithelial cells undergo volumetric cell rearrangement driven by the tissue surface tension, which directs cell movement from the surface to the core region of two-aggregate systems, cancer cells rather perform surface cell rearrangement. Cancer cells migrate toward the surface of the two-aggregate system driven by the solid stress while the surface tension is significantly reduced. The solid stress, accumulated in the core region of the two-aggregate system, is capable of suppressing the movement of epithelial cells that can undergo the jamming state transition; however, this stress enhances the movement of cancer cells. We have focused here on the multi-scale rheological modeling approaches that aimed at reproducing and understanding these biological systems.

This paper presents a study of the platinum activity in the ORR in a hydrogen polymer electrolyte membrane fuel cell with electrodes containing multi-walled CNTs in a wide range of compositions and conditions. The data of the comparative analysis of the platinum activity on a fraction of Nafion in the electrode, the composition of the oxidizing agent (oxygen, air), pressure, and temperature are provided. The reasons for the dependence of the platinum surface activity on the component composition of the electrode are considered. Specific mass activity and surface activity of platinum in the ORR in MEA with the electrodes with CNTs depend on the ionomer/platinum ratio. Both dependences have a maximum at the level of the 25% Nafion fraction. The maximum appears as a result of an optimal structure formation, which ensures the fullest use of the platinum surface and minimal concentration overvoltages. Specific mass activity and surface activity of platinum for the sample with 34% CNTs at T = 60 °C and excessive pressure of p = 2 atm amount to 0.46 A/mg and 0.72 mA/cm2, respectively.

Rational design of unique pre‐catalysts for highly active catalysts toward catalyzing the oxygen evolution reaction (OER) is a great challenge. Herein, a Co‐derived pre‐catalyst that allows gradual exposure of CoOOH that acts as the active center for OER catalysis is obtained by both phosphate ion surface functionalization and Mo inner doping. The obtained catalyst reveals an excellent OER activity with a low overpotential of 265 mV at a current density of 10 mA cm−2 and good durability in alkaline electrolyte, which is comparable to the majority of Co‐based OER catalysts. Specifically, the surface functionalization produces lots of Co‐PO4 species with oxygen vacancies which can trigger the surface self‐reconstruction of pre‐catalyst for a favorable OER reaction. Density functional theory calculations reveal that the Mo doping optimizes adsorption‐free energy of *OOH formation and thus accelerates intrinsic electrocatalytic activity. Expanding on these explorations, a series of transition metal oxide pre‐catalysts are obtained using this general design strategy. The work offers a fundamental understanding toward the correlation among surface‐structure‐activity for the pre‐catalyst design. Unravelling the intrinsic mechanism, especially what the “true” catalyst for the oxygen evolution reaction (OER) is, is still highly challenging. Herein, a Co‐based pre‐catalyst is designed that enables rational control over exposure of true active CoOOH centers by in situ self‐reconstruction to deliver excellent electrocatalytic performance, representing one of the state‐of‐the‐art OER catalysts.

Microbial enhanced oil recovery (MEOR) technology is an environmental-friendly EOR method that utilizes the microorganisms and their metabolites to recover the crude oil from reservoirs. This study aims to research the potential application of strain SL in low permeability reservoirs. Strain SL is identified as Bacillus subtilis by molecular methods. Based on the mass spectrometry, the biosurfactant produced by strain SL is characterized as lipopeptide, and the molecular weight of surfactin is 1044, 1058, 1072, 1084 Da. Strain SL produces 1320 mg/L of biosurfactant with sucrose as the sole carbon source after 72 h. With the production of biosurfactant, the surface tension of cell-free broth considerably decreases to 25.65 ± 0.64 mN/m and the interfacial tension against crude oil reaches 0.95 ± 0.22 mN/m. The biosurfactant exhibits excellent emulsification with crude oil, kerosene, octane and hexadecane. In addition, the biosurfactant possesses splendid surface activity at pH 5.0–12.0 and NaCl concentration of 10.0% (w/v), even at high temperature of 120 °C. The fermentation solution of strain SL is applied in core flooding experiments under reservoir conditions and obtains additional 5.66% of crude oil. Hence, the presented strain has tremendous potential for enhancing the oil recovery from low-permeability reservoirs.

Quaternary ammonium salts (QAS), as the surface active compounds, are widely used in medicine and industry. Their common application is responsible for the development of microbial resistance to QAS. To overcome, this issue novel surfactants, including gemini-type ones, were developed. These unique compounds are built of two hydrophilic and two hydrophobic parts. The double-head double-tail type of structure enhances their physicochemical properties (like surface activity) and biological activity and makes them a potential candidate for new drugs and disinfectants. Antimicrobial activity is mainly attributed to the biocidal action towards bacteria and fungi in their planktonic and biofilm forms, but the mode of action of gemini QAS is not yet fully understood. Moreover, gemini surfactants are of particular interest towards their application as gene carriers. Cationic charge of gemini QAS and their ability to form liposomes facilitate DNA compaction and transfection of the target cells. Multifunctional nature of gemini QAS is the reason of the long-standing research on mainly their structure-activity relationship.

This work presents a thermodynamically consistent framework that enables self-contained, predictive Köhler calculations of droplet growth and activation with considerations of surface adsorption, surface tension reduction, and non-ideal water activity for chemically complex and unresolved surface-active aerosol mixtures. The common presence of surface-active species in atmospheric aerosols is now well-established. However, the impacts of different effects driven by surface activity, in particular bulk–surface partitioning and resulting bulk depletion and/or surface tension reduction, on aerosol hygroscopic growth and cloud droplet activation remain to be generally established. Because specific characterization of key properties, including water activity and surface tension, remains exceedingly challenging for finite-sized activating droplets, a self-contained and thermodynamically consistent model framework is needed to resolve the individual effects of surface activity during droplet growth and activation. Previous frameworks have achieved this for simple aerosol mixtures, comprising at most a few well-defined chemical species. However, atmospheric aerosol mixtures and more realistic laboratory systems are typically chemically more complex and not well-defined (unresolved). Therefore, frameworks which require specific knowledge of the concentrations of all chemical species in the mixture and their composition-dependent interactions cannot be applied. For mixtures which are unresolved or where specific interactions between components are unknown, analytical models based on retrofitting can be applied, or the mixture can be represented by a proxy compound or mixture with well-known properties. However, the surface activity effects evaluated by such models cannot be independently verified. The presented model couples Köhler theory with the Gibbs adsorption and Szyszkowski-type surface tension equations. Contrary to previous thermodynamic frameworks, it is formulated on a mass basis to obtain a quantitative description of composition-dependent properties for chemically unresolved mixtures. Application of the model is illustrated by calculating cloud condensation nuclei (CCN) activity of aerosol particles comprising Nordic aquatic fulvic acid (NAFA), a chemically unresolved and strongly surface-active model atmospheric humic-like substance (HULIS), and NaCl, with dry diameters of 30–230 nm and compositions spanning the full range of relative NAFA and NaCl mixing ratios. For comparison with the model presented, several other predictive Köhler frameworks, with simplified treatments of surface-active NAFA, are also applied. Effects of NAFA surface activity are gauged via a suite of properties evaluated for growing and activating droplets. The presented framework predicts a similar influence of surface activity of the chemically complex NAFA on CCN activation as was previously shown for single, strong surfactants. Comparison to experimental CCN data shows that NAFA bulk–surface partitioning is well-represented by Gibbs adsorption thermodynamics. Contrary to several recent studies, no evidence of significantly reduced droplet surface tension at the point of activation was found. Calculations with the presented thermodynamic model show that throughout droplet growth and activation, the finite amounts of NAFA in microscopic and submicron droplets are strongly depleted from the bulk, due to bulk–surface partitioning, because surface areas for a given bulk volume are very large. As a result, both the effective hygroscopicity and ability of NAFA to reduce droplet surface tension are significantly lower in finite-sized activating droplets than in macroscopic aqueous solutions of the same overall composition. The presented framework enables the influence of surface activity on CCN activation for other chemically complex and unresolved aerosol mixtures, including actual atmospheric samples, to be systematically explored. Thermodynamic input parameters can be independently constrained from measurements, instead of being either approximated by a proxy or determined by retrofitting, potentially confounding several mechanisms influenced by surface activity.

With the material system operating at lower temperatures, protonic ceramic electrochemical cells (PCECs) can offer high energy efficiency and reliable performance for both power generation and hydrogen production, making them a promising technology for reversible energy cycling. However, PCEC faces technical challenges, particularly regarding electrode activity and durability under high current density operations. To address these challenges, we introduce a nano-architecture oxygen electrode characterized by high porosity and triple conductivity, designed to enhance catalytic activity and interfacial stability through a self-assembly approach, while maintaining scalability. Electrochemical cells incorporating this advanced electrode demonstrate robust performance, achieving a peak power density of 1.50 W cm⁻ 2 at 600 °C in fuel cell mode and a current density of 5.04 A cm −2 at 1.60 V in electrolysis mode, with enhanced stability on transient operations and thermal cycles. The underlying mechanisms are closely related to the improved surface activity and mass transfer due to the dual features of the electrode structure. Additionally, the enhanced interfacial bonding between the oxygen electrode and electrolyte contributes to increased durability and thermomechanical integrity. This study underscores the critical importance of optimizing electrode microstructure to achieve a balance between surface activity and durability. Protonic ceramic electrochemical cells, operating at lower temperatures, offer efficient power generation and hydrogen production, but they face challenges related to electrode activity and durability. Here, a scalable nano-porous electrode design enhances performance, stability, and long-term reliability.

Surfactants have been a focus of investigation in atmospheric sciences for decades due to their ability to modify the water uptake and cloud formation potential of aerosols. Surfactants adsorb at the surface and can decrease the surface tension of aqueous solutions. In microscopic aqueous droplets with finite amounts of solute, surface adsorption may simultaneously deplete the droplet bulk of the surfactant. While this mechanism is now broadly accepted, the representation in atmospheric and cloud droplet models is still not well constrained. We compare the predictions of five bulk–surface partitioning models documented in the literature to represent aerosol surface activity in Köhler calculations of cloud droplet activation. The models are applied to common aerosol systems, consisting of strong atmospheric surfactants (sodium myristate or myristic acid) and sodium chloride in a wide range of relative mixing ratios. For the same particles, the partitioning models predict similar critical droplet properties at small surfactant mass fractions, but differences between the model predictions increase significantly with the surfactant mass fraction in the particles. Furthermore, significantly different surface tensions are predicted for growing droplets at given ambient conditions along the Köhler curves. The inter-model variation for these strong surfactant particles is different than previously observed for moderately surface active atmospheric aerosol components. Our results highlight the importance of establishing bulk–surface partitioning effects in Köhler calculations for a wide range of conditions and aerosol types relevant to the atmosphere. In particular, conclusions made for a single type of surface active aerosol and surface activity model may not be immediately generalized.

A brief review of articles on the flotation of minerals using a combination of reagents is presented. It is noted that the main attention of the authors is aimed at studying the effect of the combination of collectors at the mineral-liquid interface. It was shown that one of the reagents or associates formed as a result of their joint action, possessing surface activity, can serve as a desorbed form of sorption and help reduce the induction time during the formation of a flotation complex.

The sea surface microlayer (SML) forms the < 1 mm thin ocean's boundary with the atmosphere and plays a critical role in mediating air–sea gas exchange and biogeochemical cycling. However, the biological processes shaping its molecular composition remain insufficiently understood. During a research cruise in the central Baltic Sea (Eastern Gotland Basin), we investigated how phytoplankton, including cyanobacteria, influence the biomolecular composition of the SML. Although no major bloom was detected, distinct shifts in phytoplankton composition were observed, leading to pronounced differences in biomolecular characteristics between the SML and underlying water (ULW), and between conditions characterized by high and low cyanobacteria abundance. While SML enrichment patterns and carbohydrate concentrations were comparable to those previously reported for the Western Baltic Sea, concentrations of total amino acids (TAA) and surfactants were substantially higher in this study and under cyanobacteria-dominated phytoplankton conditions. Distinct molecular signatures were associated with different phytoplankton size classes. During periods of high abundance of pico- and nanophytoplankton (P/NP; Synechococcus-dominated), the SML was characterized by elevated surfactant and total combined carbohydrate (TCCHO) concentrations. Furthermore, Synechococcus sp. co-varied with the non-protein amino acid γ-aminobutyric acid (GABA), particularly under high abundance of P/NP. This suggests that the production of surface-active organic matter may be linked to Synechococcus sp. In contrast, under high abundance of microphytoplankton (MP; filamentous and colonial cyanobacteria), particulate amino acids > 20 µm (PAA > 20 µm) and particulate combined carbohydrates > 20 µm (PCCHO > 20 µm) were elevated in the ULW, mirroring particulate organic carbon > 20 µm (POC > 20 µm) and filamentous/colonial cyanobacterial biomass patterns. The significant correlation between MP biomass and POC > 20 µm suggests that the particulate organic carbon pool was largely derived from filamentous/colonial cyanobacteria, even in the absence of a distinct bloom. Together, our results imply that phytoplankton size structure and taxonomy exert distinct biomolecular imprints on SML chemistry in the Central Baltic Sea. The contrasting roles of filamentous/colonial cyanobacteria (proteinaceous signatures) and Synechococcus sp. (carbohydrate/surface-activity imprint) imply community-dependent modulation of surface activity and indicate that future changes in biodiversity potentially impacts air–sea gas exchange in the ocean.